A related art bi-directional optical transmitting and receiving apparatus generally has a structure in which a TO-CAN-based optical transmission unit and an optical reception unit are aligned in a single metal housing and fixed by a laser welder, allowing light to be reflected or transmitted by an optical filter mounted within the housing so as to be bi-directionally optically coupled.
When an active optical alignment method using a laser welder is used, two TO-CAN packages can easily be optically aligned, but a large number of components such as the two TO-CAN packages, a metal housing, and the like, may incur a high cost, lead to an increase in processing steps, and significantly degrade mass-producibility.
In an effort to solve the above-detailed problems, a bi-directional optical transmitting and receiving apparatus capable of performing the transmission and reception of optical signal bi-directionally by using a single TO-CAN package has been proposed, but disadvantageously, it has the high possibility of electro-optical crosstalk occurring due to the structure thereof, in which a transmission unit and a reception unit are mounted in the same space within the single TO-CAN package.
Thus, in order to reduce the possibility of the occurrence of electro-optical crosstalk, a method of fabricating a separate lid having a 45-degree sloped surface to isolate the reception unit has been proposed. However, with this method, since an additional lid is provided besides an existing lid, fabrication costs and processing costs are increased, and a hole should be formed in a portion of the 45-degree sloped surface for optical coupling to a reception unit light receiving element. Also, since the size of the hole cannot be reduced structurally, there is a limitation in reducing electro-optical crosstalk, and in case of a WDM (Wavelength Division Multiplexing) filter for diverging input light and output light, only an optical filter manufactured in the form of a thin film on glass should be used and an internal lid having the WDM optical filter should be actively aligned for optical coupling.
Also, in the case of the foregoing related art, a structure manufactured for the respective elements are mounted in a sub-mount form, rather than in the form of a platform, making it difficult to optically align them and increasing process costs and process time. In addition, a long bonding wire and a lead wire are required, having a difficulty in transmitting a high speed signal.